The invention concerns a method and an equipment for the automatic detection of undesired video scenes from a current television transmission, which is achieved by the evaluation of frames, in particular initial frames, of the undesired video scenes.
By many transmitting stations, the current transmissions are interrupted and promotional contributions are faded in. These promotional contributions represent a disturbing interruption for most of the viewers. Proposals are already known in order to suppress the disturbing promotional contributions. One of these proposals is to switch the sound off during the promotional contribution. The patent specification U.S. Pat. No. 3,870,956 shows a circuit which suppresses the sound of the promotional contribution for a predetermined time. For this purpose, an operating person (the viewer) must actuate the corresponding key of a remote control transmitter at the beginning of the promotion. When however only the sound is interrupted, the viewer has still to observe the promotional contributions.
An equipment with a mode which permits the observation of the promotional contribution to be circumvented by the actuation of the transmitting station selecting keys or of the pause key is known from the document EP 0 384 388 A1. Whilst the program of another transmitting station can be viewed, an information that a preset time span has run down is faded in on the picture screen of the television receiver so that the viewer can return to the original transmitting station.
It is a disadvantage of the aforementioned proposals that the viewer must always press a key at the beginning of the promotion in order to suppress the promotional contribution. It is furthermore disadvantageous that, due to the run-down of a fixedly preset time, the end of the respective promotional contribution can not be determined exactly.
These disadvantages are avoided in the description, which is described in the German Patent Specification DE 41 06 246 C1, by the beginning and end of a promotional contribution, after a single identification and storage of the frames characterising the beginning and the end of promotional blocks by an operating person, being recognised automatically by the equipment. Thus, the automatic suppression of promotional contributions is possible without losing desired program information.
After the transmitting institutions have often gone over to characterising only still the beginning of a promotional block by a special image, it is no longer possible by means of the known equipment to recognise the renewed beginning of the transmission interrupted by the promotional block. For that reason, the uninterrupted transmission is not automatically displayed again after termination of the promotional block.
It is evident from the preceding explanations that it is imperative for the fading-out, for example of a promotional transmission received as undesired transmission contribution, to be able to perform an unobjectionable identification of such a transmission contribution also when this is not marked by identification signals at the transmitter end.
The unobjectionable identification and its timely detection of so-called undesired video scenes is however necessary also for statistical investigation and for commercial reasons. When a promotional transmission order is given, it can be proved at a receiving location, for example by identification, that this promotional contribution is also radiated in its full length. For the detection of such picture signals, a method for the re-recognition of unique image signals, in particular of unique image sequences, is known from the DE 43 09 957 C1, according to which method luminance values of predetermined pixels and preferably predetermined groups of pixels (clusters) are scanned. In a further method step, a different signal between the luminance values of the predetermined clusters is formed and a mark function is derived from this. For each complete frame, a binary feature vector thus arises, the length of which corresponds with the number of the clusters scanned for each full frame. For a predetermined number of successive full frames (for example 51), a frame sequence feature vector is then formed, which is brought up to date after each full frame. After each full frame, the up-dated feature vector is correlated with a plurality of feature vectors, which are determined in the same manner, and identify the stored frame sequences to be recognised again. For a predetermined correlation value, a signal "frame sequence recognised again" is produced. It is possible in this manner to detect a promotional transmission which is regarded as an undesired video scene in the sense of the present application, but can however also count as a desired one. With appropriate selection of the clusters and time determination during the reception of a video scene at the beginning and at the end, the signals in that case give an exact information about the length of the scene which has been received so that an image scene association (individual promotional spot) as well as also a detection of the transmission, which has taken place altogether, of the undesired video scene is possible. These known methods are however not designed for also being able to evaluate images in front of the undesired scene and after the undesired scene in order for example to be able to detect into which scene portion of a current television transmission, for example of a film, these video scenes have been introduced or even to be able to be utilised for fading out the undesired image scene.